单体应用并发实际场景(保持余额操做的正确:数据库余额字段版)

单体应用并发实际场景(保持余额操做的正确:数据库余额字段版)

树冢
2021-11-15 / 0 评论 / 7 阅读 / 正在检测是否收录...

数据库余额表:本来想用版本号来实现的,后面弃用version字段。

DROP TABLE IF EXISTS `t_test`;
CREATE TABLE `t_test` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `account` decimal(11,2) DEFAULT NULL,
  `version` int(100) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;

INSERT INTO `t_test` VALUES ('1', '50.00', '1');

mapper.xml文件:仔细看两个sql的写法,这里是重点,请不要在java代码中进行余额的加减操做。

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.taotao.mapper.TTestMapper" >
  <resultMap id="BaseResultMap" type="com.taotao.pojo.TTest" >
    <id column="id" property="id" jdbcType="INTEGER" />
    <result column="account" property="account" jdbcType="DECIMAL" />
    <result column="version" property="version" jdbcType="INTEGER" />
  </resultMap>

  <update id="updateAccountAdd" parameterType="com.taotao.pojo.TTest" >
    update t_test
    set account = account + #{newAccount,jdbcType=DECIMAL}
    where id = #{id,jdbcType=INTEGER}
  </update>

  <update id="updateAccountSub" parameterType="com.taotao.pojo.TTest" >
    update t_test
    set account = account - #{newAccount,jdbcType=DECIMAL}
    where id = #{id,jdbcType=INTEGER} and account >= #{newAccount,jdbcType=DECIMAL}
  </update>

</mapper>

service:请在每一个方法上加入事物和synchronized。

@Service
public class TestServiceImpl implements TestService {

    @Autowired
    private TTestMapper testMapper;

    /**
     * 存钱
     *
     * @param money
     */
    @Override
    @Transactional
    public synchronized BigDecimal addAcount(String name, int money) throws TransactionalException {

        TTest tTest = testMapper.selectByPrimaryKey(1);
        tTest.setNewAccount(new BigDecimal(money));

        int i = testMapper.updateAccountAdd(tTest);
        if (i == 0){
            System.out.println("添加余额失败!余额=" + tTest.getAccount());
            return new BigDecimal(money);
        }

        System.out.println(name + "...存入:" + money + "..." + Thread.currentThread().getName());

        return selectAcount(name);
    }

    /**
     * 取钱
     *
     * @param money
     */
    @Override
    @Transactional
    public synchronized BigDecimal subAcount(String name, int money) throws TransactionalException{

        TTest tTest = testMapper.selectByPrimaryKey(1);
        tTest.setNewAccount(new BigDecimal(money));
        int i = testMapper.updateAccountSub(tTest);
        if (i == 0){
            System.out.println("帐户余额不足!余额=" + tTest.getAccount());
            return new BigDecimal(money);
        }

        System.out.println(name + "...取出:" + money + "..." + Thread.currentThread().getName());

        return selectAcount(name);
    }

    /**
     * 查询余额
     */
    @Override
    @Transactional
    public synchronized BigDecimal selectAcount(String name) throws TransactionalException{

        TTest tTest = testMapper.selectByPrimaryKey(1);

        System.out.println(name + "...余额:" + tTest.getAccount());

        return tTest.getAccount();
    }
}
@Controller
public class TestMysqlController {

    @Autowired
    private TestService testService;

    @RequestMapping(value="/cardAddAcountMysql")
    @ResponseBody
    public TaotaoResult<Integer> cardAddAcount() throws TransactionalException{
        TaotaoResult<Integer> result = new TaotaoResult<Integer>();
        result.setData("+100, 余额: " + testService.addAcount("card", 100));
        return  result;
    }

    @RequestMapping(value="/passbookAddAcountMysql")
    @ResponseBody
    public TaotaoResult<Integer> passbookAddAcount() throws TransactionalException{
        TaotaoResult<Integer> result = new TaotaoResult<Integer>();

        result.setData("+100, 余额: " + testService.addAcount("存折", 100));
        return  result;
    }

    @RequestMapping(value="/cardSubAcountMysql")
    @ResponseBody
    public TaotaoResult<Integer> cardSubAcount(){
        TaotaoResult<Integer> result = new TaotaoResult<Integer>();
        result.setData("-150, 余额: " + testService.subAcount("card", 150));
        return  result;
    }

    @RequestMapping(value="/passbookSubAcountMysql")
    @ResponseBody
    public TaotaoResult<Integer> passbookSubAcount() throws TransactionalException{
        TaotaoResult<Integer> result = new TaotaoResult<Integer>();

        result.setData("-200, 余额: " + testService.subAcount("存折", 200));
        return  result;
    }

    @RequestMapping(value="/selectAcountMysql")
    @ResponseBody
    public TaotaoResult<Integer> selectAcount() throws TransactionalException {
        TaotaoResult<Integer> result = new TaotaoResult<Integer>();

        result.setData(testService.selectAcount(""));

        return  result;
    }


}
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